Recently, a so-called layout scanner was invented and put to practical use in some fields, which adopts steps of inputting multiple picture data and letter (drawing) data obtained from respective input scanners to respective large capacity memory units such as a disc memory, displaying both data on a monitoring device such as a CRT displaying unit, assembling both data to be a complete image with use of such as a digitizer under control of a CPU (central processing unit).
In this kind of system, letter (drawing) data can be obtained from scanning of a letter copy as well as for picture data, which method is disclosed in Japanese Patent Applicatons Nos. 57-6650, 57-18184, 57-39877 and corresponding U.S. applications Ser. Nos. 459,157 now U.S. Pat. No. 4,556,901; 464,907 now U.S. Pat. No. 4,580,060 and 471,869 now U.S. Pat. No. 4,553,172 assigned to the assignee of this invention.
Such a layout scanner system adopts steps of inputting data corresponding to the picture and letter components to a large capacity memory device such as a disc memory, laying out the picture and the letter components corresponding to the stored data onto a desired area of one sheet with use of a monitoring device such as a CRT displaying device and a digitizer, storing the determined image as data into certain cells of designated addresses of the disc memory in order to output the determined image for final printing, outputting said data from the disc memory to a raster-scanning recording device, and exposing a film to a beam modulated by the determined data to record thus laid-out images.
Meanwhile, ordinary printing machines can print a rather large size sheet such as A1 (594.times.841 mm) size paper at a time. Therefore provided that a page unit is A4 (210.times.297 mm) size and a sheet in a printing process such as for printing magazines, is A1 size eight said A4 size page units are assembled onto one print sheet. This assembly procedure means that certain page units are automatically assembled for a bookbending process on a photosensitive film in proper directions and positions in a film producing process beforehand to be proper in order and lengthwise, and said procedure usually considers margins.
Conventional imposition procedure is usually rearranged owing to a method of folding a print sheet, that is, the procedure is carried out according to conduct of an operator who places each page unit successively onto a transparent base film, the scale of which is the same as the print sheet, while confirming a sample of the method of folding the print sheet. But this method requires the operator on keep close watch to the directions and positions of the page units, resulting in inefficiency.
FIG. 1 shows an example of the imposition procedure, in which the observe (a) and reverse (b) faces of an A1 size print sheet carrying eight A4 size page units are given. Thus assembled final print sheet is folded orderly to be a determined scale and is trimmed to be a book. In FIG. 1, the numbers are actual page numbers for publishing, and the directions of the numbers shows the actual directions of reproduced images.
For example, the square numbered 4 in FIG. 1(a) indicates a reproduced image the top of which faces the right side and the bottom of which faces the left side, which means it will be properly situated in the finally bound items (pamphlet, magazine, etc.). FIG. 2 is a detail of FIG. 1, wherein a, b, c and d are margins and gutters for cutting and folding. Meanwhile thickness of a folded sheet is varied according to the number of page units and when saddle stitching (often used for magazines or catalogues) is adopted for bookbinding, there must be some difference in gutter width between page units which are to be inner pages and page units which are to be outer pages. Therefore, measures of said margins and gutters a, b, c, d are to be varied according to the number of assembled page units or binding method, which leads to a difficult work task even for experienced operators. Furthermore, when the desired prints must be colored, more accuracy is required in placing page units onto transparent sheets, which also results in inefficient operation.